Basics of Construction Planning

Drafting a construction plan

A construction plan turns drawings into a job that can be done. Steps to draft it:

1. Study the goal and the drawings: size, place, materials, date needed.
2. Break the work into tasks: dig, footing, walls, roof, finishing.
3. Fix the order: a task that needs another must wait. Walls cannot start until the footing has hardened.
4. Estimate the time for each task from the quantity and how much a team does per day.
5. Draw a bar chart (Gantt chart): each task is a bar, its length is its days, its place shows when it starts.
6. Plan the resources: workers, tools, materials and when they must arrive.

Weather matters. In farm areas, plan concrete work for the dry season and allow spare days.

Temporary works planning

Temporary works are things we build only to make the job possible or safe. They are removed when the job ends. Examples:

• Scaffold: a frame of poles and boards to stand on at height.
• Formwork: a mould of wood or steel that holds wet concrete until it hardens.
• Shoring and propping: supports for trenches or slabs.
• Fence and signs: keep people and animals out.
• Site shed and store: for tools, cement and records.
• Access road, water and power: so trucks, workers and machines can reach the job.
• Dewatering: pumping or draining water out of a pit.

Plan where each goes, who builds it, how strong it must be (a scaffold must carry workers and materials), and when it is removed. Temporary works cost money and time, and many accidents come from badly built ones, so they are part of the plan and the cost.

Specifications

A specification is a written description of the quality of materials and of the work. The drawing shows where and how big; the specification says what and how good.

It includes: the material and grade (cement type, concrete mix 1:2:4, steel grade), sizes (brick size, bar diameter), how to do the work (mix, pour, cure for 7 days), tests to pass, and the standard or code to follow. Example lines: "Footing concrete 1:2:4, 0.4 m wide, 0.4 m deep, cured 7 days" and "Walls in first-class brick, 230 mm thick, cement mortar 1:6".

It is part of the contract, so the buyer, the builder and the inspector all agree on the quality.

Cost estimation

An estimate is a calculated guess of the cost before building. Steps:

1. Take off quantities from the drawings: concrete in m³, wall in m², steel in kg, roof in m².
2. Choose unit prices (rates): price per m³, m², kg or day of labour.
3. Multiply: cost of an item = quantity × rate.
4. Add: total of all items, plus temporary works, plus a small allowance for waste and surprises (contingency), plus the contractor's overhead and profit.

Example: footing concrete = perimeter 20 m × 0.4 m × 0.4 m = 3.2 m³. At 6000 per m³ this costs 19 200. Wall = 20 × 2.5 m − 2 m² (door) = 48 m². At 800 per m² this costs 38 400. Together 57 600 before the extras.

Estimates also help us compare designs and decide what we can afford. Compare the estimate with the real cost later to improve the next estimate.

Try it: plan a tent

Plan putting up a small tent at home. List the tasks (clear the ground, lay the sheet, fix poles, tie ropes). Mark the order. Give each a time. Draw a bar chart on squared paper. What helps you but is not the tent itself? (A stool, a rope marker, a torch.) Those are your temporary works.

Key formulas and definitions

• Plan = tasks + order + time + resources
• Bar chart: bar length = task days; start = after the job it depends on
• Quantity (volume) = length × width × depth
• Cost of an item = quantity × rate
• Total = sum of items + temporary works + contingency + overhead

Worked examples

Common mistakes

• Starting a job before the job it depends on is finished, such as walls on soft concrete.
• Forgetting temporary works in the cost and the time.
• Writing a specification that says only "good quality" with no numbers or standards.
• Leaving out waste and extras, so the real cost passes the estimate.